RabbitMQ——消息发布订阅

消息订阅发布

一个生产者，多个消费者
每个消费者都有自己的队列
生产者，没有直接把消息发送到队列，而是先发送到交换机
每个队列都要绑定到交换机
生产者发送的消息经过交换机，到达队列，就能实现一个消息被多个消费者消费

话不多说，直接撸代码：

老套路，首先还是生产者：

public class Send {

    private static final String EXCHANGE_NAME = "test_exchange";

    public static void main(String[] args) throws IOException, TimeoutException {
        Connection connection = RabbitConnection.getConnection(); //看前面文章写的工具类
        Channel channel = connection.createChannel();
        channel.exchangeDeclare(EXCHANGE_NAME, "fanout"); //声明exchange，这里为什么是fanout待会下面解释
        //send a msg
        String msg = "hello exchange";
        channel.basicPublish(EXCHANGE_NAME, "", null, msg.getBytes());
        System.out.println("send:"+msg);
        channel.close();
        connection.close();
    }
}

消费者1：

public class ReceiveOne {
    private static final String QUEUE_NAME = "receive1_queue";  //这里我们重新申请一个新的队列
    private static final String EXCHANGE_NAME = "test_exchange";

    public static void main(String[] args) throws IOException, TimeoutException {
        Connection connection = RabbitConnection.getConnection();
        Channel channel = connection.createChannel();
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);

        channel.basicQos(1);
        channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, ""); //这里需要绑定exchange,其他的和前面的work_queue是一样的

        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [ConsumerOne is] Received '" + message + "'");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }finally {
                channel.basicAck(delivery.getEnvelope().getDeliveryTag(),false);  //这里是手动应答
            }
        };
        boolean autoAck = false;
        channel.basicConsume(QUEUE_NAME, autoAck, deliverCallback, consumerTag -> { });
    }
}

消费者2：

public class ReceiveTwo {

    private static final String QUEUE_NAME = "receive2_queue";
    private static final String EXCHANGE_NAME = "test_exchange";


    public static void main(String[] args) throws IOException, TimeoutException {
    Connection connection = RabbitConnection.getConnection();
    Channel channel = connection.createChannel();
    channel.queueDeclare(QUEUE_NAME, false, false, false, null);

    channel.basicQos(1);
    channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "");

    DeliverCallback deliverCallback = (consumerTag, delivery) -> {
        String message = new String(delivery.getBody(), "UTF-8");
        System.out.println(" [ConsumerTwo is] Received '" + message + "'");
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            channel.basicAck(delivery.getEnvelope().getDeliveryTag(),false);  //这里是手动应答
        }
    };
    boolean autoAck = false;
    channel.basicConsume(QUEUE_NAME, autoAck, deliverCallback, consumerTag -> { });    }
}